Waste material such as trees, brush, stumps, pallets, railroad ties, peat moss, paper, wet organic materials and the like are often processed with hammermill machines that generally fall into one of two categories: grinders or shredders. Grinders typically function by forcing the material into contact with a rotating drum having cutters at the outer diameter. The cutters of grinders travel at a relatively high rate of speed, typically exceeding 5000 feet per minute. Shredders typically function by forcing the material into contact with a rotating drum with cutters at the outer diameter. The cutters of shredders travel at a relatively low rate of speed, typically less than 500 feet per minute.
An example of one grinder is disclosed in commonly assigned U.S. Pat. No. 5,507,441 dated Apr. 16, 1996. Other examples of grinders are found in U.S. Pat. Nos. 5,419,502; 5,975,443; 5,947,395; and 6,299,082. Examples of shredders are found in U.S. Pat. Nos. 4,927,088; 5,971,305; and 6,394,376.
In both types of hammermill machines, the cutters are subjected to extreme loads. Although the loading differs, due to the differing speeds, the cutters in either machine can experience high rates of wear, particularly if the waste material is abrasive. For this reason the cutters are typically replaceable.
One such replaceable cutter design utilizes a through-member, as part of the basic structure of the drum, to support cutters, and is shown in commonly assigned U.S. Pat. No. 6,422,495 dated Jul. 23, 2002, which is herein incorporated by reference. FIG. 1 of the present disclosure illustrates the through-member design of U.S. Pat. No. 6,422,495. As shown in FIG. 1, the through-member 10 is supported and guided in a drum skin 20 by a sleeve 30. Cutters 40 are interconnected to the through-member 10 at each end of the through-member (only one end shown). The cutters 40 interact with shoulders 32 formed on the sleeve 30. By the interaction of cutter 40 with shoulder 32 of the sleeve 30, the through-member 10 is held in a first axial and radial position.
This interaction of the cutter 40 with the shoulder 32 (i.e. the restriction of axial and radial movement of the cutter) makes the supporting profile of shoulder 32, relative to the cutter 40, critical to the function of the machine. In this prior art design, the shoulder 32 is a part of the sleeve 30, and is not meant to be removable, as it is welded to drum skin 20. In different applications requiring different cutters, there may be a need to have various supporting cutter profiles. Thus, a need exists for a shoulder or supporting cutter profile that enables the use of a variety of cutters.
Likewise there exists a need for improved support of a through-member. It has been found that hammermill machines create significant dynamic radial loads on the cutters 40; which in turn, subject the supporting shoulders 32 of the sleeves 30 to loads sufficient to cause permanent deformations. Thus, a need exists for an improved mounting arrangement that restricts the movement of a through-member relative to a sleeve.
Alternative mounting arrangements have been used, including wedge blocks. One example of a wedge block can be found in U.S. Pat. No. 6,523,768. In this example, a drums includes pockets having a narrow outer opening with a wider inner recess, herein referred to as a closing taper. Wedges having a wide base and narrow top are installed into the pocket with a bolt. The bolt pushes against a bottom of the pocket, forcing the wedges outward to wedge against a cutter. This design requires relatively complex pocket manufacturing and assembly.
Another example of a drum that uses a wedging technique to restrain cutters is disclosed in EP 1 201 310 A1. In this example, a pair of mating hammers, each having a tapered surface, cooperate to extend from a pocket formed through a drum. The hammers have intersecting centers, and include parallel sides. The tapered surfaces of the hammers cooperate to wedge the hammers apart and force the hammers into contact with the drum. In this example, when a hammer is worn, the entire hammer needs to be replaced. The hammers are long and relatively complex. Thus, a need exists for a simpler, more cost effective mounting arrangement.